1. Field of the Invention
The present invention relates to a technique of viewing stereo images, and more particularly, to a pair of shutter glasses utilized for viewing stereo images presented by a video output apparatus and a method for controlling the pair of shutter glasses.
2. Description of the Prior Art
With the development of science and technology, users are pursing stereoscopic and more real image displays rather than high quality images. There are two techniques of present stereo image display. One is to use a video output apparatus, which collaborates with glasses (such as anaglyph glasses, polarization glasses or shutter glasses), while the other one is to use only a video output apparatus without any accompanying glasses. No matter which technique is utilized, the main theory of stereo image display is to make the left eye and the right eye see different images, thus the brain will regard the different images seen from two eyes as stereo images.
For a pair of shutter glasses, they are widely used for users to view stereo images presented by a video output apparatus. The pair of shutter glasses comprises two shutter lenses. By the shutter lenses switching properly between an on-state and an off-state, user's left eye is allowed to see left-eye images and user's right eye is allowed to see right-eye images. In general, each shutter lens of the pair of shutter glasses is switched to an on-state and an off-state, alternately. For example, when the shutter lens corresponding to the left eye is in an on-state, the shutter lens corresponding to the right eye is in an off-state, and vice versa. Therefore, the ambient brightness user feels is lower than real ambient brightness. On the other hand, according to the polarized direction of image light output presented by the video output apparatus, the shutter lenses of the pair of shutter glasses have a related polarization setting. However, ambient light comprise light beams of different angles. When the shutter lens of the pair of shutter glasses is in an on-state, only light beams which conform to the polarization setting of the shutter lens will penetrate the shutter lens, and thus the ambient brightness the user feels will also be lower than the real ambient brightness. If the user feels lacking of ambient brightness when wearing the pair of shutter glasses, he/she may not see items (such as a keyboard or remote control) beyond the screen of the video output apparatus clearly, leading to inconvenience in stereo image viewing for users.
Moreover, suppose that a liquid crystal layer is utilized in the shutter lens of the pair of shutter glasses to control the switching between an on-state and an off-state. In general, when there is no voltage applied to the liquid crystal layer, the shutter lens is in an on-state and allows light beams to penetrate therethrough. As is described above, under the control of well known control mechanism, the two shutter lenses of the pair of shutter glasses stay in an on-state alternately. Therefore, when there is no voltage applied to the liquid crystal layer of one shutter lens for allowing light beams to penetrate therethrough, the liquid crystal layer of the other one of shutter lens requires voltage applied thereto for blocking light beams from penetrating therethrough. Thus, if the shutter lens stays in an off-state longer, the power consumption of the pair of shutter glasses is increased.
In conclusion, how to increase the ambient brightness the user feels when wearing pair of shutter glasses and/or decrease power consumption of pair of shutter glasses without affecting user's viewing of stereo images for users is an issue to be solved immediately in this technical field.